Why does the acquire button spin, but no aquisition takes place?

If you're in DSO Mode, most likely you have set a trigger that is not being satisfied by your input. Try turning off the trigger to sample the input first and ensure your trigger is in range.

If you're in Logger Mode, then the spinning icon means the logger is running. You can retrieve the data by tapping the "Retrieve" icon below. Tap the spinning button again to stop the logger.